Patients with severe emphysema typically have lung segments within a lobe that are significantly more diseased than other segments within that lobe. These more diseased segments of a lobe typically are more hyperinflated, and have the poorest function (gas exchange).
Reducing hyperinflation by reducing lung volume in patients with emphysema has been shown to improve pulmonary function and quality of life. Many current techniques to achieve LVR focus on an entire lung lobe without regard to variance in disease state among the segments of the lobe. For example, valves implanted in the lung rely on blockage of ventilation and subsequent atelectasis of an entire lobe to create LVR. Valves must occlude all segments of a lobe in order to achieve safe and effective LVR. This is because collateral ventilation occurs between segments within a lobe, and therefore all segments must be blocked in order for that lobe to have ventilation effectively blocked in its current embodiment.
Coils implanted in the lung rely on tissue retraction to create LVR. Coils are typically placed in up to 10 segments of each lung (upper and lower lobes). The therapy is reported to improve elastic recoil by whole lung reduction. A treatment regimen for coils targeting the most diseased segments is problematic as tissue retraction does not work as well in the most highly diseased segments due to lack of tissue to grab. Additionally, a large number of segments must be retracted with coils, making targeting less feasible.
Glue/foam therapy relies on blocking non-adjacent sub-segments with glue. Therefore if a two adjacent segments are both highly diseased one of those highly diseased sub-segments will not be reduced. Additionally, glue is delivered at the sub-segmental level due to limitations with patient tolerance of inflammatory reaction to glue.